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IndustryArena Forum > CNC Electronics > Spindles / VFD > Thermistor in ATC spindle
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  1. #1
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    Thermistor in ATC spindle

    Hello everyone,
    I just got a Chinese ATC spindle that comes with a PTC 140 Thermistor and it has two cables coming out of the spindle that are about 24AWG. I contacted the manufacturer and they said the signal is either open or closed depending on if it's safe or not to operate the spindle (I tested it with a multimeter and its normally open). My question is how do I go about connecting this to either a Richauto controller or a relay connected to an alarm/warning light? the Richauto controller has an input for an alarm, it sends a 24v signal and when the signal is returned via the ground terminal the alarm gets triggered. The Richauto manual says it's for the alarm output on servo motors ( I don't have servos). Does anyone know if it's safe to send a 24v signal coming out of the rich auto or a power supply from a relay to a thermistor? Am I getting this totally wrong? has anyone done something similar with these Chinese ATC spindles?

    BTW the manufacturer said the thermistor output gets triggered at 180C/356F witch is pretty hot!! they said it's because it's internal and "the internal insulation of this spindle will be destroyed at a high temperature above 180C ,but in theory and practice, the spindle's internal temperature will not reach such a high temperature". I still think thats pretty hot!.

    Thank you and I really appreciate any help.

  2. #2
    Community Moderator Al_The_Man's Avatar
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    Re: Thermistor in ATC spindle

    Quote Originally Posted by joztheshark View Post
    Hello everyone,
    I just got a Chinese ATC spindle that comes with a PTC 140 Thermistor and it has two cables coming out of the spindle that are about 24AWG. I contacted the manufacturer and they said the signal is either open or closed depending on if it's safe or not to operate the spindle (I tested it with a multimeter and its normally open). My question is how do I go about connecting this to either a Richauto controller or a relay connected to an alarm/warning light? the Richauto controller has an input for an alarm, it sends a 24v signal and when the signal is returned via the ground terminal the alarm gets triggered. The Richauto manual says it's for the alarm output on servo motors ( I don't have servos). Does anyone know if it's safe to send a 24v signal coming out of the rich auto or a power supply from a relay to a thermistor? Am I getting this totally wrong? has anyone done something similar with these Chinese ATC spindles?

    BTW the manufacturer said the thermistor output gets triggered at 180C/356F witch is pretty hot!! they said it's because it's internal and "the internal insulation of this spindle will be destroyed at a high temperature above 180C ,but in theory and practice, the spindle's internal temperature will not reach such a high temperature". I still think thats pretty hot!.

    Thank you and I really appreciate any help.
    Strange comment from the manuf, "The thermal switch is either on or off" , thermistors change resistance with temperature, and are usually around 1.5k.( PTC = Positive Temperature Coefficient)
    Thermal SWITCHES are either on or off.
    If in fact it is a thermistor, then you would need a circuit based around a schmitt trigger device or IC etc.
    Are you in fact sure it is not a thermal switch?
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  3. #3
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    Jan 2005
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    Re: Thermistor in ATC spindle

    Quote Originally Posted by joztheshark View Post
    Hello everyone,
    I just got a Chinese ATC spindle that comes with a PTC 140 Thermistor and it has two cables coming out of the spindle that are about 24AWG. I contacted the manufacturer and they said the signal is either open or closed depending on if it's safe or not to operate the spindle (I tested it with a multimeter and its normally open). My question is how do I go about connecting this to either a Richauto controller or a relay connected to an alarm/warning light? the Richauto controller has an input for an alarm, it sends a 24v signal and when the signal is returned via the ground terminal the alarm gets triggered. The Richauto manual says it's for the alarm output on servo motors ( I don't have servos). Does anyone know if it's safe to send a 24v signal coming out of the rich auto or a power supply from a relay to a thermistor? Am I getting this totally wrong? has anyone done something similar with these Chinese ATC spindles?

    BTW the manufacturer said the thermistor output gets triggered at 180C/356F witch is pretty hot!! they said it's because it's internal and "the internal insulation of this spindle will be destroyed at a high temperature above 180C ,but in theory and practice, the spindle's internal temperature will not reach such a high temperature". I still think thats pretty hot!.

    Thank you and I really appreciate any help.
    You would connect this to your VFD Drive the Drive would then shut down, if this switch closed, the Drive fault circuit is connected into your EStop circuit, this is just an over temperature switch no voltage should be used in it's circuit it is just a switch
    Mactec54

  4. #4
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    Re: Thermistor in ATC spindle

    Quote Originally Posted by Al_The_Man View Post
    Strange comment from the manuf, "The thermal switch is either on or off" , thermistors change resistance with temperature, and are usually around 1.5k.( PTC = Positive Temperature Coefficient)
    Thermal SWITCHES are either on or off.
    If in fact it is a thermistor, then you would need a circuit based around a schmitt trigger device or IC etc.
    Are you in fact sure it is not a thermal switch?
    I also thought that was strange. I think they were trying to explain that it is a thermal switch, a thermistor connected to a mechanism that makes the connection on or off.

  5. #5
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    Re: Thermistor in ATC spindle

    Quote Originally Posted by mactec54 View Post
    You would connect this to your VFD Drive the Drive would then shut down, if this switch closed, the Drive fault circuit is connected into your EStop circuit, this is just an over temperature switch no voltage should be used in it's circuit it is just a switch
    This makes a lot of sense, I'll try connecting it this way. But wouldn't the VDF have a voltage for the switch to work? for the VDF to know the switch is closed wouldn't it need electrons flowing from one terminal to the other? But if in fact I have a thermal switch in the spindle and not just a thermistor then I guess a voltage wouldn't hurt it.

    I really appreciate the help from everyone.

  6. #6
    Community Moderator Al_The_Man's Avatar
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    Re: Thermistor in ATC spindle

    Quote Originally Posted by joztheshark View Post
    I also thought that was strange. I think they were trying to explain that it is a thermal switch, a thermistor connected to a mechanism that makes the connection on or off.
    So where did you get PTC 150 thermistor?
    Contact closure sensor would be used on a input to the VFD that would source or sink an input, usually Opto isolated.
    Therefore if so, no external supply needed.
    They normally come N/C and open on overheat.
    It would be one or the other, thermistor or thermal switch, not both.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

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